A conventional vehicle light control device described in JP-A-10-315844 includes an upper side illuminance sensor for detecting an external illuminance at an upper side of the vehicle, and a control portion for controlling turning on or off operation of vehicle lights. The control portion determines whether or not the illuminance detected by the upper side illuminance sensor reaches a predetermined reference illuminance, and controls the turning on or off operation based on this determination.
Furthermore, this vehicle light control device includes a vehicle speed sensor for detecting a vehicle speed, and a light condition setting means. As the vehicle speed increases, the light condition setting means increases the reference illuminance, and decreases a delay time. Here, the delay time is a time from a determination time where it is determined whether or not the detected illuminance reaches the reference illuminance up to an illumination time of the vehicle lights.
Accordingly, when the vehicle runs at a high speed, the reference illuminance is high and the delay time is short. Therefore, when the vehicle runs under an elevated bridge at a high speed, the lights may be momentarily turned on and off, and a passenger in a leading vehicle or an oncoming vehicle may mistakenly feel this turning on or off operation as a passing.
Furthermore, lights provided around an entrance and an exit of a tunnel are generally brighter compared with lights provided inside the tunnel in order to reduce a drastic change in lighting between the inside and the outside of the tunnel on an expressway. Thus, the headlights of the vehicle may be not instantly turned on based on the vehicle speed even when the vehicle enters the tunnel. As described above, in this vehicle light control device, because the reference illuminance and the delay time are controlled by the vehicle speed, it is difficult to suitably control the vehicle lights in accordance with the exterior environment of the vehicle, due to the control being based on the vehicle speed.